id = 2074
title = "riscv64  cannot use the mret instruction to jump to the address corresponding to s mode"
state = "closed"
created_at = "2024-01-05T08:17:33.034Z"
closed_at = "2024-01-18T06:49:14.552Z"
labels = ["target: riscv"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2074"
host-os = "Linux"
host-arch = "x86"
qemu-version = "QEMU emulator version 8.1.90"
guest-os = "coreboot/bios"
guest-arch = "riscv"
description = """I use coreboot to boot my linux kernel.The kernel is copied at 0x82200000,I set reg mepc 0x82200000,and set reg mstatus a00000800.
and I use "mret" instruction so that qemu can jump to 0x82200000 and enter S mode.But some errors happened.
It shows:
[DEBUG]  Exception:          Instruction access fault
[DEBUG]  Hart ID:            0
[DEBUG]  Previous mode:      machine
[DEBUG]  Bad instruction pc: 0x8103f7c0
[DEBUG]  Bad address:        0x00000000
[DEBUG]  Stored ra:          0x8103f7b8
[DEBUG]  Stored sp:          0x82032f08
Bad instruction pc: 0x8103f7c0 in my elf file instruction is "mret".
So I can not jump to my kernel's load address.
I think when I use -bios option,my qemu should in M mode.How could I can jump to my mepc address?"""
reproduce = """1.download qemu
2.download coreboot"""
additional = """When I enter qemu with -bios option,I find that the reg mstatus is 0xa0000000."""